Floating contaminant constraining fence

ABSTRACT

A floating contaminant constraining fence structure wherein the fence is assembled from a plurality of modular fence sections to enclose at least part of a selected water surface area, each of the fence sections including vertically elongated strut members having buoyant devices to support them at a selected level in the water, stringers connecting the tops and bottoms of the strut members and plural sets of harness ropes for supporting the modular fence sections in a desired arrangement, together with a cloth web extending above and below the water level supported by the stringers. The method of laying out such a floating fence structure, and settling tank structure usable therewith are also disclosed.

Unite States Patent 3,499,291 3/1970 Mikkelsen OTHER REFERENCES Oil Industry (pub) Feb. 1970, page 84.

Primary Examiner-Jacob Shapiro v Attorney-Mason, Fenwick & Lawrence ABSTRACT: A floating contaminant constraining fence structure wherein the fence is assembled from a plurality of modular fence sections to enclose at least part of a selected water surface area, each of the fence sections including vertically elongated strut members having buoyant devices to support them at a selected level in the water, stringers connecting the tops and bottoms of the strut members and plural sets of harness ropes for supporting the modular fence sections in a desired arrangement, together with a cloth web extending above and below the water level supported by the stringers. The method of laying out such a floating fence structure, and

settling tank struc tu re usable therewith are also disclosed.

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SHEET 12 05 12 INVENTOR g EUGENEW.NEWTON L masm zx 'mm-Qu We ATTORNEYS FLOATING CONTAMINANT CONSTRAINING FENCE BACKGROUND OF THE INVENTION volume such as oil and its byproducts, chemical contaminants and the like on bodies of water such as rivers, harbors, bays, coastal waters and open seas, and wherein the containment fence apparatus can be readily flown to the site where it may be required and assembled and moored at the site of use. Contaminant collector vessels may be associated with the stationary and sweeping fence structures to accumulate contaminant skimmed from the water for transportation to disposal points. The widespread use of large sea going tankers for transporting liquid products such as crude oil and refined petroleum products have created a dangerous pollution problem, arising from either spills from the tankers during unloading or leaks, collisions, or accidents at sea. Since the crude oil or petroleum products have a density lower than sea water, they will float and rapidly spread over wide areas. The contamination of public beaches and destruction to wildlife as well as alteration of the ecology of the sea resulting from contamination produced by leakage from such tankers or accidental collisions, sinkings and other sea accidents, have received wide attention in the press and aroused great public concern. F issures in the sea floor in the vicinity of offshore oil drilling operationsformed of inflatable or buoyant floats, sometimes with underwater skirts, have been proposed to contain the lighter than water contaminants, especially in harbor areas immcdiately surrounding unloading tankers and like structures. However, most of these devices are unsuitable for use in the open sea because of the wave forces normally encountered in open seas, and also are inadequately stabilized to contain the contaminant in volume under these conditions and withstand tidal forces in tide water areas. The complications resulting from tides, currents, wave motion, winds, and the pressures resulting from the weight of the materials contained introduce considerable problems in the proper design an anchoring of containment structures for confining lighter than water floating contaminants. Also, the possibility of occurrence of pollution from leakage of such lighter than water contaminants in unpredictable fashion in any part of the world makes it desirable that the contaminant containment device be of such nature that it can be readily flown to any site where it may be required and promptly assembled and stabilized in position. The containment device should be a complete packaged unit that can be air freighted from strategic locations to the point of need, and therefore the weight and bulk limitations of the package must be within the ranges which can be readily handled by air freight or helicopters available for transporting such devices.

Also, the anchoring, mooring, buoyancy and stability provisions of the containment apparatus must be such that the apparatus will successfully withstand the stresses of tides, currents, winds and waves and still effectively contain the lighter than water contaminant material floating on the water surface.

Accordingly an object of the present invention is the provision of a floating fence assembly which may be readily transported to a site where lighter than water contaminants may have begun pollution of the surface of a body of water and which may be quickly stabilized in position and moored to effectively contain the contaminants in volume, both over a substantial vertical depth of contaminant as well as over the enclosed area.

Another object of the present invention is provision of a floating fence assembly as described in the preceding paragraph, which will successfully withstand the stress of tides, currents, winds and waves and provide effective containment of oil contaminants and the like floating on a water surface.

- Another object of the present invention is the provision of a novel containment fence structure which can be readily assembled from sections or module units to form an anchored fence or a sweeping fence for accumulating lighter than water contaminants.

Yet another object of the present invention is the provision of a cloth and inflated tube collector vessel structure usable with the fence structure to accumulate the contaminant for transportation to disposal points.

Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a top plan view of a first embodiment of the contaminant containing fence structure of the present invention;

FIG. 1A is a diagram of the layout: plan for the positioning grid rope patterns for the embodiment of FIG. 1;

FIG. 1B is a top plan view of a circular fence arrangement incorporating the principles of the embodiment of FIG. 1;

FIG. 2 is a vertical section view taken along the line 2-2 of FIG. 1;

FIG. 3 is a vertical section view to enlarged scale, taken along the line 3-3 of FIG. 1, illustrating the construction of the fence struts;

FIG. 4 is fragmentary side elevation view of the top portion of a strut, showing the construction for securing the strut to a horizontal rope member;

FIG. 5 is a fragmentary elevation view illustrating the construction for securing two adjacent fence cloths together, nd showing the vertical strut connection used to connect horizontal rope members at IOO-feet section connection points with shackle-type fitting at top and bottom of strut, viewed from the plane indicated at 55 of FIG. 3;

FIG. 6 is an elevation view illustrating the construction of the rope clamp for releasably coupling the struts to the horizontal ropes;

FIGS. 7A and 7B are elevation views to enlarged scale of an outer grid rope connection and an inner grid rope connection, respectively;

FIG. 8 is an elevation view of a float construction which may be used with the present invention;

FIG. 9 is a fragmentary perspective view of an alternate type of connection fitting for coupling the :struts to horizontal steel tubing;

FIG. 10 is a perspective view of a spring fastener which may be employed with the present invention to releasably connect components together;

FIG. 11 is a side elevation view, with parts broken away, of the suction float assembly;

FIG. 12 is a section view of the suction chamber device, taken along the line 12-12 of FIG. 11;

FIG. 13 is a top plan view of another embodiment of a containment fence assembly;

FIG. 13A is a top plan view of a larger fence assembly similar to the embodiment shown in FIG. 13, demonstrating the use of the module principle to enclose any size ship or underwater leakage; I

FIG. 14 is a diagram of the anchor and fence positioning grid for the embodiment of FIG. 14;

FIG. 15 is a somewhat diagrammatic top plan view of another embodiment of the containment fence arranged as a sweeping fence assembly;

FIG. 15A is a fragmentary perspective view of a portion of the sweeping fence;

FIG. 16 is a fragmentary perspective view of an inlet portion of a settling tank vessel usable with the: fence structure;

FIGS. 17. an 18 are perspective views, with parts broken away, of settling tank vessels;

FIG. 19 is a section view of the vessel of FIG. 18, and

FIG. 20 is a perspective view of another form of a settling tank vessel.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to the first embodiment shown in FIGS. 1 and 2, there is shown in plan view in FIG. 1 an assembled contaminant containment fence, generally indicated by the reference character 15, extending in a generally oval shaped pattern defined by two semicircular end portions and by straight intervening fence portions surrounding a contaminant area. The fence I5 is made up of two types of fence segments or modules, the semicircular end portions being made up of curved fence sections or modules 16 and the straight intervening fence portions being made up of straight fence sections 17. Each fence section 16, 17 is, in the preferred embodiment, a IOO-foot section and comprises a plurality of horizontally spaced, vertical struts 18 spaced horizontally approximately feet on centers and formed of spring steel tubing to support a fence cloth 32 as later described. While in certain low stress applications the vertical strut may be a single spring steel tube, I prefer to form the strut of a pair of strut tubes, including a first strut tube 19 which is slightly bowed and a second strut tube 20 which is more predominantly bowed, that is the second strut tube 20 is bowed about a smaller radius, the two strut tubes 19 and 20 being interconnected at spaced vertical intervals by horizontal bracing tubes 21. The vertical struts 18 are of bowed shape so that when the tidal currents are pushing the fence cloth against the concave edge ofthe strut on the uptide side of the fence (which occurs twice daily), the pressure of the cloth against the strut automatically turns it so that the strength of the strut is always opposing the pressure of the cloth.

The top and bottom ends of the first and second strut tubes 19 and 20 in one embodiment are welded to each other and to a rope coupling 22 such, for example, as a Crosby clip formed of a U-shaped member 220 wherein the bend portion is welded to the tubes 19 and 20 and the threaded ends extend through openings in a clamping bar 22b and are secured by threaded nuts. An upper horizontal rope member or cable 23 and a lower horizontal rope member or cable 24, each for example formed of l-inch diameter nylon rope about 100 feet long, are secured in the rope couplings 22 at the tops and bottoms of the plurality of struts 18 spaced 10 feet apart and forming the respective modules 16 or 17, the struts being preferably preassembled to the upper end lower ropes 23 and 24 for each fence section or module.

In a alternative embodiment, the rope couplings 22 may be dispensed with and a pivoted rope clamp indicated at 25 in FIG. 6 may be employed at each of the upper and lower ends of each strut for releasably connecting the associated struts to the ropes 23 and 24. This rope clamp 25, as illustrated in FIG. 6, comprises a first leg 26 which is of tubular cylindrical configuration over most of its length and is fitted over and welded to the first strut tube 19 of the associated strut, and includes a second leg 27 pivoted to the first leg 26 at pivot point 28 and having a generally U-shaped cross section over most of its lower portion opening toward the companion leg 26 to permit the leg 27 to be swung about the pivot 28 into partially surrounding relation with the second strut tube 20. The confronting,concavely curved upper portions of the legs of the clamp clamp tightly about the rope member 23 or 24 when the leg 27 is in the clamping position illustrated in FIG. 6. Holes are provided in the second strut tube 20 and the second leg 27 of the clamp which register when the leg 27 is in the closed position illustrated, to receive a fastening member such as the spring fastener 29 to be later described in detail. Such units may be transported with the struts separate from the ropes 23, 24 and assembled at the contamination site, the ropes 23, 24 in such cases being preferably premarked at lO-foot intervals to indicate where the strut clamps 25 should be located.

The more prominently bowed second-strut tube 20 of the plurality of struts making up the fence section have an inflatable float 30 removably secured thereto, for example formed as a vertically elongated bagof neoprene-coated nylon cloth having an inflation valve 30a thereon and upper and lower mounting flange formations 30b having grommet reinforced openings therein to register with openings in the second strut tube 20 of the associated strut and be removably fastened thereto by other spring fasteners 29. The strut tubes 19 and 20 may be hollow metallic tubes, such as stainless steel, and may, if desired, be filled with styrofoam or similar closed cell expanded plastic to improve buoyancy.

The upper and lower rope members 23 and 24 of each fence section support a fence cloth 32, which in the preferred example is 8- or 16-ounce neoprene-coated nylon cloth having a length of approximately 1% times the l00foot length of the horizontal rope members on the curved end sections and a vertical width of approximately 1% times the vertical spacing between the ropes 23 and 24, to allow the fence cloth to form a half-circle thereby eliminating most of the strain on the cloth under thestress of the tide currents and wave action when viewed in vertical section. Also, the horizontal length of the cloth 32 is about 1 /2 times the length of the module at the bends on curved portions.

The upper and lower edges of the fence cloth 32 are formed with a border loop 33 by folding the edge of the cloth back upon itself and securing it with a line of stitching and liquid nylon glue, providing a pair of horizontal border loops through which the upper or lower rope member 23, 24 extends. The border loop 33 is, of course, interrupted at the location of each strut 18 by a cutout or inset to expose the upper and lower end portions of each strut, the fence cloth being folded against itself and provided with reinforcing tape and stitching along the boundaries of eachsuch cutout or inset, as indicated at 34 in FIG. 5, where the rope couplings 22 protrude to exposed positions. Similar reinforcing tape and stitching 34 is provided at end cutouts in the border loops 33 at the opposite ends of each IOO-foot fence cloth section, and the opposite ends of each horizontal rope member 23 and 24 are preferably provided with an eye splice 35 formed about a rope thimble 36, to provide adjacent loops in the rope members 23 and 24 at the adjacent ends of each fence section which can be secured together by a suitable shackle or releasable coupling device 37. If desired, a vertically spaced pair of shackles 37 may be secured together by welding them to the ends of a vertical rod or tube 38 to form a connecting shackle assembly 38 for adjacent fence sections.

Also, the vertical edges at the opposite ends of the fence cloth 32 for each fence section are provided with vertical loop formations 39, 39A by folding the vertical ends of the fence cloth back upon the adjoining cloth portions an appropriate distance and stitching and nylon gluing them, and the loop formations 39, 39A are formed into interfitting loop segments 39', 39A by cutting through them horizontally at vertically spaced intervals, for example 2-inch intervals, and cutting vertically through the bend along the alternate loop segments 39" of the loop formation 39 at one end and through the relatively staggered loop segments 39A of the other end, so that the loop segments may-be interfitted as illustrated in FIG. 5 and secured together by a steel rod 40 for securing the fence cloths' of successive fence sections together. An opening is left in these loop segments, for example by cutting out a lapping pair of segments 39', 39A at a location about 2% feet below the water line to leave an opening for a grid line to pass through the fence, as later described.

Each of the curved fence sections 16 are also provided with two sets of inwardly extending fence harness ropes 41 and two sets of outwardly extending fence harness ropes 42 adjacent the opposite ends of the sections, formed for example of 36- inch nylon rope, which converge together to inner harness connecting rings 43 and outer harness connecting rings 44, respectively spaced, for example, about 60 feet from the fence cloth. Each of the respective sets of harness ropes, for example the set 14-1 of section 16-1 is designed to form a convergent pattern of harness ropes with another set, such as set 41-2 of section 16-2, as indicated in FIG. 1, with the shackle assembly 313 connecting cloth sections 16-1 and 16-2 at the center or bisector of the convergent pattern. The lengths of the harness ropes 41, 42 for the curved sections 16 are chosen to cause the upper and lower horizontal rope members 23 and 24 and the fence cloth 32 to assume a selected radius of curvature in top plan, for example a radius of about 200 feet. The straight fence sections 17 each also include pairs of sets of fence harness ropes 41' and 42' extending to inner connecting rings 43' and outer connecting rings 44 with the harness ropes of appropriate lengths to maintain the upper and lower horizontal rope members 23, 24 for the straight sections 17 in a straight vertical plane.

The inner harness connecting rings 43' are designed to be connected to inflatable floats 45A, to be later described, which sustain near the water surface the-coupling points for positioning grid ropes 46. The grid ropes 46 in the first embodiment extend inwardly along axes transverse to the major longitudinal axis of the oval pattern, and are connected by shackles or similar releasable couplings 47 to other inflatable floats 45B at a longitudinal center grid rope 48. The transverse grid rope 46 may be, for example, /z-inch nylon ropes, and the longitudinal center grid rope 48 may be a l /-inch nylon rope. Connections 49A and 49B are provided at the upstream and downstream ends of the longitudinal center grid rope 48, for connection to radial grid ropes 50A, 50B, 50C for coupling the longitudinal center grid rope to the curved fence sections 16. The grid ropes 50A may, for example, be l-inch diameter nylon ropes, the grid ropes 50B may be Viz-inch diameter nylon ropes, and the grid ropes 50C may be 41-inch diameter nylon ropes. An exemplary type of inner grid connection is illustrated in FIG. 73, wherein the harness ropes from two adjoining fence sections, for example ropes 41-1 and 41-2, are secured about 43-inch weldless pear-shaped rings 43-1 and 43-2, which together with an eye in the end of grid rope 46-1 are coupled to safety hooks 43A assembled by shackles 433 to weldless end links 43C assembled on another shackle, like shackle 43D, positioned 90 from the position shown in HQ. 73 and coupled to a section of the transverse grid rope 46 extending inwardly to the longitudinal center grid rope 48. The float 45A is connected to the inner grid connection by a chain and safety hook 45A-1 coupled on one of the end links 43C.

The outer harness connecting rings 44, 44 of both the straight fence sections 17 and the curved fence sections 16 are also designed to be coupled by shackle assemblies 106A as shown in FIG. 7A, to mooring float rings, such as indicated at 51A, interconnecting outside grid rope sections 52 and coupled to inflatable mooring floats 45C. As in the case of the inside grid connections, the harness ropes 42-1 and 42-2 are preferably formed about rings 44-1 and 44-2, which together with the grid rope section 46-1 are coupled on safety hooks 44A assembled with shackles 44B and links 44C on shackle 44D coupled to the float ring 51A. A pair, or more if needed, of floats 45C are connected by a chain and snap hook 45C-1 to the ring 51A. An anchor rope 53, having for example a 60- pound Danforth anchor 53' on its lower end, is coupled to the shackle 44D by a shackle 53A, safety hook 53B and weldless link 53C, the anchor rope running through the shackle 53A about a pulley thereon and being adjusted by a suitable stop device 53D. The stop devicemay be formed for example of a socket member 53D-1 through which the anchor rope passes having an upwardly opening tapered socket, and a split wedge member 5313-2 whose halves surround the rope and are connected together by hinge wires 53D-3, whereby the wedge portions are urged together as they enter the tapered socket and securely clamp the anchor rope. The wedge portions which engage the anchor rope may be ribbed to facilitate gripping of the anchor rope. The upper end of the anchor rope 53 is maintained on the surface by a float similar to those used at the grid connections.

An anchor buoy float 54 is preferably provided for each of the anchors, connected to the crown or fluke end of the anchor by an anchor release rope 54a. Each anchor buoy is preferably provided with warning flasher and/or a bell mounted on a bracket extending upwardly from the float. The anchor buoy float 54 is provided as a shipping warning marker and also to permit the anchor to be lifted from the region of the flukes and thereby facilitate breaking out of the anchor when it is desired to remove the contaminant fence.

An outside obstruction net, in the form of a large mesh net circling the containment fence, may be provided when desired at the outer grid ropes 52 to extend entirely around the fence, and is indicated generally by the reference character 55. its purpose is merely to prevent the floating fence from being damaged by floating objects when the obstruction net is used, the lower net rope at its lower edge may be connected to the float chains of chain and snap hook assemblies 45C-l about 2% feet below the water line, and the upper net rope may be connected to the top connections to float 45C. The top net rope may also have floats spaced on it, iifdesired.

It will be noted from FIGS. 1 and 1A. that diagonal grid connecting ropes 56 extend along inclined axes from the upstream and downstream connectors 49A and 4913 to the inner harness connecting rings 43' joining transverse grid rope 46' to the middle straight fence sections 17 forming a diamond pattern, and anchor ropes 57 extend from these last mentioned connecting rings 43 to provide additional bracing of the fence assembly. Also, the outer connecting rings 44 for the curved fence sections 16 connected to the radial grid ropes 50A and 5013 have, in the illustrated embodiment, three anchor ropes 53 extending therefrom to three different anchors, and have an additional number of floats like the floats 45C to sustain the harness connecting rings for these curved fence sections near the water surface.

The floats 45A, 45B, and 45C and 54 previously described may be of any desired inflated balloon-type construction, or may preferably for close multiple connection purposes be formed as a cube, an octagonal solid, or other similar configuration, having the faces 58 thereof cut from sheets of l6 ounce neoprene coated nylon cloth seamed and sealed together along all edges 58 and having double triangular connection plates 59 at the upper and lower edges for connection to mooring shackles and, in the case of the anchor buoy floats 54, to support brackets 59A and 59B on which are mounted a warning flasher 60 ad a bell 61 to identify the location of the anchor buoy float. For simplicity, these floats are merely indicated as circles in the top plan views and diagrammatic views. The floats are of two sizes: 300-pound displacement for anchor buoy floats, and 2,000-pound displacement for other floats.

In certain applications where additional rigidity in fence construction is desired and in lieu of use of upper and lower horizontal ropes 23 and 24, an alternate construction may be employed, wherein the first and second strut tubes 19 and 20 of each strut 18 may be secured to a tubular Tee connection fitting 63, the adjacent ends of the strut tubes 19 and 20 extending into and being welded and pinned in the leg member 64 of the Tee connection fitting which is in turn welded to a tubular crosspiece 65 and braced by suitable angle braces 66. The tubular crosspiece 65 is of appropriate diameter to receive into the bore thereof adjacent ends of two 2-inch diameter spring steel tubes 66A, 66B, each having a length of approximately 10 feet. These 2-inch spring steel horizontal tubes, generally indicated by the reference character 66, form the upper and lower horizontal connecting members for the successive struts 18 and displace the upper and lower ropes 23 and 24 used in the previously described embodiment. To releasably connect the ends of the horizontal tubes 66 in the crosspiece 65 of the Tee connection fitting 63, the ends of the tubes 66 and corresponding portions of the crosspiece 65 are provided with openings arranged on two diametric axes at right angles to each other and spaced from each other along the axes of the tubes 66, to receive fasteners such as the spring fasteners 29 therethrough.

The spring fasteners 29 employed in various portions of the fence structure, may be of the construction illustrated in FIG. 10, comprising a single piece of spring steel wire, for example %-inch spring steel wire for the 2-inch horizontal tube connections and one-eighth inch or one-sixteenth inch for the others having a straight leg 29A of pin like nature adapted to be inserted through the registering apertures of the members to be fastened together, and including a spring coil portion 29B of several turns and a curved latching leg 29C terminating in an offset lip or hook formation 29C adapted to be sprung about the free end portion of the leg 29A in the manner illustrated in FIG. 10-.

To install the contaminant containment fence in proper position at the contamination site, assuming one positioning boat and one anchoring boat is being used, the series of grid ropes are first laid out in a predetermined pattern. The positioning boat is first anchored in the running tide so that the bow is over the center of the leakage or source of contamination to determine the center of the fence and direction of tide. The longitudinal center grid line 48 is first assembled, with the positioning boat located at the position indicated in broken lines at 70, providing for example, one float at each inside grid connecting pint and two or more floats, as required, at the outside grid connecting points, for the transverse grid lines 46, 46'. The anchoring boat will then take this assembly up-tide, as directed, by positioning boat, until upper half of assembly is paid out, and the anchoring boat will proceed to lay out the radial grid rope 50A and paying out the proper length anchor rope for the middle anchor line indicated at 71 in FIG. 1 for the upstream curved fence section 17. Additional floats 45 should be provided at the anchor rope and fence harness connection points associated with this fence section.

' The positioning boat then, starting from position 70, proceeds down-tide or down-current, laying out the downstream portion of the center grid rope 48 and the center one of the downstream anchors 72. Final adjustments of paralleling the center grid line 48 with the tide or current are made by installing the two additional anchor lines 72A at the downtitle end of the center grid line and then applying the two additional anchor lines 71A flanking the anchor line 71 at the uptide end, and tightening the anchor rope to achieve the desired alignment.

The positioning boat when proceeds to the hub of the grid at the up-tide end, at the coupling point 49A by paying out the radial grid ropes 50B and the three anchors associated therewith and then proceeding to the down-tide end and similarly paying out the downstream radial grid ropes 50B and the three anchor lines associated with those grid ropes. Next, the diamond-forming diagonal lines indicated by the ropes 56 and the transverse grid rope 46' through the starting positions 70 are connected and laid out and the anchor lines and associated floats for the center transverse grid line 46 are then set. The up-tide radial grid lines 50C and their associated anchor lines are then laid out, and the positioning boat then works down-tide or downstream setting the remaining transverse grid lines 46 and their associated anchor lines, and the downstream radial grid lines 50C and their associated anchor lines in that order. It will be noted that throughout the previously described procedure, the outside grid ropes 52 assist in setting the proper angles between the ropes making up the radial lines from the up-tide and down-tide hubs and also assist in properly spacing the transverse grid lines and their associated anchor lines.

After laying out the grid as previously described, the curved fence segments 16 can then be assembled by coupling their inner and outer harness connecting rings 43, 44 to the appropriate grid rings by the, safety snap hook assemblies illustrated in FIGS. 7A and 78, then coupling the eye splices 35 at the ends of the upper and lower horizontal rope members 23, 24 with the coupling shackles 37, and connecting the adjacent ends of the sections of fence cloth 32 together by inserting the steel rod 40 through the vertical loop segments 39 in interleaved fashion at the locations of the grid ropes 46 and 50A-50C with the grid ropes passing through the openings left in the loop segments.

After the contaminant containment fence is completely assembled, a suction float unit, such as that indicated at 75 in F 16$. 11 and 12, may be placed within the space contained by the fence 15. This suction float unit 75 may comprise an annular or donut shaped inflated tube 76 supported on a wheel rim structure or spiders 77, below which a suction chamber device 78 is removably suspended by bolts extending through suitable openings in the wheel rim structure 77. The suction chamber device 78 includes a flat circular bottom portion 78A adapted to underlie the inflated tubes 76, a flat circular top portion 78B of smaller diameter, and a vertical concave curved wall portion 78C bounding a circumferential portion of the top portion 78B and a pipe section 78D extending through the curved wall 78C in overlying relation to the bottom 78A and having a standard hose connection 78D at its outer end. Baffle plates 78E extend in a fan-shaped pattern from the circular edge of top plate 783 toward the center of bottom 78A over a selected distance, the float unit 75 being thus so arranged that the bottom 78A will be positioned by the inflated tube 76 at an appropriate level to cause the oil or other lighter than water contaminants in the region of the suction float unit 75 to be drawn 0E into the region between baffles 785 and through the pipe section 78D and the hose and pump unit to be connected thereto for withdrawing the contaminant from the contained zone, for example into a settling tank vessel such as illustrated in FIG. 20 and later described, having valve means for releasing fluid from the bottom of the vessel to indicate when the vessel is full of contaminant.

Instead of using the suction float unit 25 to withdraw the contaminant from the containment zone, an oil settling tank vessel of the types illustrated in FIGS. 16-19, to be later described, can be provided at either en d of the fence, where tidal currents permit, to act as a self cleaning agent from which the contaminant can be ultimately pumped.

A circular form of constraining fence formed entirely of curved fence modules 16 and embodying the same principles as the fence assembly of FIGS. 1 and 1A is shown in FIG. 18.

Another form of elongated floating containment fence construction is illustrated in FIGS. 13, 13A and 14, wherein the center longitudinal grid rope and the center sections of the transverse grid ropes connected thereto and the radial grid ropes are eliminated, by substituting grid cables connecting the inside harnesses to provide a considerably simplified anchoring grid. This arrangement permits a much larger ship to be enclosed in a given length of fence and still retain the necessary fence stability, while the anchoring of the horizontal fence members at each end tends to equalize the stress on all components. In the arrangement shown in FIGS. 13 and 14, the diameter of the fence at the upstream and downstream ends is reduced to reduce the tidal stress on the anchoring grid, but enough curve is retained to eliminate the possibility of a siphoning effect from tidal currents. With this arrangement, an inside grid formed of cable sections, for example of one and /2-inch nylon cable indicated by reference character 101 is designed to extend along curved paths from a pointed upstream connection with a temporary longitudinal grid line 102 to a pointed downstream connection with the same temporary line 102. The purpose of the temporary grid line 102 is to give the proper length for the grid to control the curve of the inside grid cables 101 to each side of this longitudinal center axis. The longitudinal center line may be a 74-inch rope, and may be dispensed with in most cases of exposed ship wreck to be surrounded by the fencebecause the inside grid cables 101 will straddle the ship and provide the appropriate spreading or curving for the inside grid ropes. Upstream and downstream extension center ropes, which may be l /-inch diameter nylon rope, indicated at reference character 103, extend from the float connections 103A and 1033 between the inside grid cables 101 and the center grid rope 102 an appropriate distance and are connected at float connection points 1104A and 1043 to outside grid rope sections 105 which may be %-inch nylon ropes.

interconnecting grid ropes 106, for example 36-inch nylon ropes having eye splices at each end like the grid rope 4-6-1 of the previously described embodiment, extend between the inside grid cable 10l and the outside grid ropes 1105 and are coupled to the outside grid ropes 105 at the float connection assemblies 106A formed by shackle and safety snap hoop units as illustrated in FIG. 7A and to the inside grid cable 101 by inside float connection assemblies lltlfiB formed of shackles and safety snap hook units as illustrated in FIG. 7B. Likewise, anchor cables indicated by the reference character 53 are coupled to the outside float connection assemblies 106A in the same manner as illustrated in FIG. 7A describing the similar outside grid connections for the first embodiment. Plural anchor lines and anchors appropriate to the stresses to be encountered are connected to various upstream and downstream end portions of the grid ropes I05 at the float connection assemblies 106A as indicated for example in FIGS. I3 and 14, and single anchor lines 53 are laid out and the anchors set for most of the lateral outside float connection assemblies 106A as indicated in the drawings.

After laying out the grid thus described in a manner similar to the laying out of the grid for the first embodiment, the fence is erected by assembling curved fence segments 16 having appropriate curvature, which may be used throughout if desired, or by using some curved fence segments 16 and some straight fence segments 17. These fence segments 16 and/or 17 are assembled as previously described by coupling their inner and outer harness connecting rings 43, 44 to the appropriate grid rings by the safety snap hook assemblies as illustrated in FIGS. 7A and 713, after which the eye splices at the ends of the upper and lower horizontal rope members 23, 24 are coupled with the coupling shackles 37 and the adjacent ends of the fence cloth 32 at the location of each grid rope 106 are connected together by inserting the steel rod 4t) through the vertical loop segments 39 with the grid ropes 106 passing through the openings therefor left in the loop segments. To further stabilize the fence at the upstream and downstream ends, two sets of 1-inch ropes 107 to either side of the longitudinal center axis are connected to the top and bottom fence horizontal members, for example at the shackles 37 at the top and bottom of struts 33 at the locations indicated in FIGS. 13 and 14- and are connected to the outer grid rope 1G5 as indicated, and additional sets of l /zinch ropes 108 may extend longitudinally from the associated inside float connection assemblies 1068 at the locations indicated and to the outside grid ropes 105, each joining the outside grid ropes at locations of outside float connection assemblies 106A to which plural anchor lines are connected.

The particular example illustrated in FIG. 13 provides an appropriate fence configuration for a fence having a major axis dimension of about 1,200 feet, but it will be appreciated that containment fences of much greater length may be formed by increasing the number of sections and appropriately changing the length of the temporary center grid rope 102. For example, a fence having a major axis length of 2,200 feet as illustrated in FIG. I3A can be readily assembled by coupling together l 1 grid rope sections and fence section at each side of the center line 102.

FIG. 15 illustrates an assembly of five curved fence sections 16 and two straight fence sections 17, together with purse string ropes 111 an towing ropes 112, providing a generally U- shaped fence assembly 113 which can be drawn by two boats for sweeping contaminants from a constricted zone until the contaminant is all collected within the U-shaped pattern defined by the fence sections, after which the purse string ropes 92 can be pulled to draw together the upstream edges of the straight fence sections 17 (the lowermost ends as viewed in FIG. 15) and thereby close the fence about the contaminant. In the sweeping fence, the struts will preferably have a llll height of only about 3 to 4 feet, the buoy floats will be located as near as possible to the bottoms of the struts, and the cloth 113A will have a vertical width of about 2% times the strut height. In this sweeping fence construction, the cloth 113A has a cloth pocket 113B, shown in FIG. 15A, at the vertical center thereof, in which is contained an upper air filled tube 1113C and a lower water-filled tube Illl3D, respectively about 12 inches and 8 inches in vertical depth, spanning the horizontal length of the respective fence module. The use of the fence cloth of about 2% times the vertical height of the struts gives a greater range of movement of the center portion of the fence cloth relative to the struts and thus in coaction with the tubes 113C and 113D, keeps the fence in proper alignment with the water surface. Alternatively, the sweeping fence assembly 113 may be provided with settling tank vessels indicated in phantom lines in FIG. 15 at reference characters 115, connected to the downstream or trailing portion of the sweeping fence to receive and accumulate the contaminant.

Examples of the settling tank vessels 1 15 which may be used to accumulate the oil and some water at the surface region are illustrated in FIGS. 16, I7, 118 and 19. In each case, an inlet or transition section 116 as illustrated in FIG. 16, providing a trough or sluice which extends from an elevation slightly above water level to just below the water level, is defined by a pair of sides formed of a plurality of vertically arranged horizontal air filled tubes 1117 and a downstream wall formation 118 having a pair of vertically spaced horizontal air filled tube sections 1180 held in the desired spacing in a flattened doughnut configuration by a connecting flap 118C to define openings 1181) between the sections 118a. A bottom 119 of, for example, neoprene nylon cloth is secured in any desired manner to the bottom of the lowermost of the air-filled side tubes 11117 to span the width therebetween, and is releasably secured to the top of the lowermost of the transverse air filled tubes 1118a by means such as a zipper or splice rod 119a. The connecting flap 118a permits the mouth portion defined by the tube sections 1118a to be opened, by disconnecting the flap 1180, to a sufficient size to allow the rib cage 121, later described, to be inserted and to permit a man to enter the vessel for repair purposes. The upstream edge of the bottom cloth 119 is also secured to the neoprene fence cloth 32 by similar zipper or splice rod connection means at a location adjacent the water level, the fence cloth portions above the level of the zipper connection 1119b being omitted in the region between the side air-filled tubes 117 with the vertical cloth edges adjacent the side wall tubes similarly zipper connected thereto, so that the mixture of oil and water within the fence can pass into the trough formation defined between the side tubes 117 and the bottom I19.

Trailing downstream from the perforate wall 118 of the inlet section 116 is the receptacle portion 120 of the vessel which, in the embodiment illustrated in FIG. I7 is of generally cylindrical configuration defined by water-filled circular tube members 1210, vertical center water-filled tube members 1211b, and longitudinal tube members 121: located as desired, for example at the top and bottom, collectively defining a rib cage I211 covered by a skin 121d, for example of neoprene cloth secured as by straps of the like to the ribs, together with air-filled tubing members 121s at the top to assist in flotation of the vessel at the proper level. The receptacle portion has a mouth configuration 122 at its front end communicating through the openings 1118b in the downstream wall 118 of the inlet section 116 for passage of the oil and water mixture which enters the trough formation into the receptacle portion 120. Suitable valved water connections and valved air connections are provide to the tubes 121 to establish the desired flotation level for the vessel, and guy ropes 123 connect the mouth portion with the upper and lower ends of the fence struts 18 flanking the inlet section 116 to adjust the location of the mouth so that the mouth is at the proper level when current flow, caused by tide or sweeping movement of the fence, is sufficient to operate the settling tank principle, so that oil and water mixture will enter the trough formation, and to cause the lower lip of the mouth to float just above the oil level when such current flow from tide or movement is not lustrated in FIG. 16, but wherein the receptacle portion 126 is of generally rectangular cross section. In this embodiment, the receptacle portion 126 is formed with generally U-shaped tubular rib members 127 interconnected by top and bottom longitudinal tubes 127A designed to be filled with water from conventional valved water connections at the top of the vessel, and horizontal transverse top air-filled tube members 128 interconnected by longitudinal tubes 128A, the rib members being covered by neoprene nylon cloth skin 129 and being braced at appropriate locations by struts 130 constructed like the struts 18 of the fence. In each of the settling tank vessels 115 and 125, the receptacle portion 126 is provided preferably with a zipper 131 or similar releasable seam formations across the lower rear portion of the skin, which maybe opened by zipper operating ropes 131a from above the surface to open the skin at the lower rib portion of the receptacle to allow water to be sucked out or exit from the lower portion of the vessel. Air valve connections, in addition to water valve connections, are provided to the tubes 127A and a water outlet tube extends from the bottom of the rib cage through the top of the vessel, so the water can be forced out of the tubes 127, 127A, or 121, by pressurized air.

Each of the settling tank vessels of FIGS. 17 or 18 may have a contaminant level indicator, generally designated by the reference character 132, formed for example of a float 132a and indicator stick 13212 guided for vertical movement in the receptacle portion, the float having appropriate buoyancy to remain at the lvel of separation between the contaminant and water within the receptacle portion.

It will be appreciated that where tidal currents are strong enough to utilize the settling tank principle, a section of containment fence having the appropriate cutout and zipper portions 11% for connection to such a settling tank vessel can be provided at the downstream end of a stationary anchored containment fence and one of the settling tank vessels 115 or 125 coupled thereto to utilize the tidal currents for accumulating the water and oil mixture in a settling tank vessel which, after filling, can be detached and replaced by another like vessel while the filled vessel is transported to a disposal area.

FIG. 20 illustrates a settling tank vessel 135 which may be used with any of the previously described containment fences to collect the containment withdrawn by the suction float unit 75. The vessel 135 has a generally cylindrical tank portion 136 formed by a neoprene nylon cloth body, without any rib cage, and has a pair of upper tubes 137 forming generally rectangular flotation loops about the top of the vessel to support the cloth body. A first valved fitting 138 in the upper portion of the vessel is provided to be connected to the hose from the pump coupled to the suction float unit 75 for delivering the contaminant and water mix collected by unit 75 to the tank portion 136. An air inlet valved fitting 139 is also provided. A valved pressure relief outlet 140 is connected through tube 141 to the bottom of the tank portion 136.

The vessel 135 is normally in collapsed condition to facilitate transportation to the contamination site. Upon arrival at the site, the upper flotation tubes 137 are inflated through valved air inlets 137a, to float the vessel, and the valved fitting 138 is connected to the pump discharge hose to feed the withdrawn contaminant and water mix collected by unit 75 to the tank portion 136. As the pressure rises in the tank portion, the pressure maintains the cylindrical shape of the tank portion without any rib cage structure. The relief outlet 140 is set to pass fluid when the pressure reaches a selected level, such as p.s.i. or less, and since the tube'141 connects contaminant. When contaminant beginsto discharge through the relief valve, the operator knows that the tank is full of contarninant.

Tow 'ropes 142 extend about the vessel, having front coupling rings 142a on forward extensions of the tow ropes and rear coupling rings 1421: where the ropes transversely cross the rear of the tank portion 136. This arrangement permits multiple vessels 135 to be connected in a train when desired. Reinforcing is preferably provided under the tow ropes and at the leading edges of the cloth forming the tank portion, for protection during towing.

To empty the vessel 135,'air pressure from an appropriate source is merely connected to the valved fitting 139, to blow the contaminant out through the tube 141 and relief outlet 140 when the vessel has been moved to a suitable location. The vessel can then be rolled up and is ready for reuse, or left filled with air for easy towing.

Whatis claimed is:

1. A method of installing in position in the water a contaminant constraining floating fence structure made up of plural, releasably connectable, modular fence sections to be assembled together to enclose a selected water surface area, the modular floating fence sections being of the type having plural vertically arranged struts to be sustained at a selected level in the water with top and bottom stringers therebetween and a fence cloth spanning the horizontal length of the section and supported along its upper and lower edges by the stringers, and sets of inner and outer harness ropes extending from the tops and bottoms of the struts; the method comprising the to the bottom of the tank, water will discharge through the relief valve 140 until the tank fills with the lighter-than-water steps of laying out inner and outer grid rope patterns defining inner and outer harness connection points and interconnecting grid ropes for locating the modular fence sections in proper relationship to surround the surface area to be enclosed, connecting buoy floats to the inner and outer harness connection points to sustain the connection points at identifiable locations near the water surface, laying out anchor lines connected to the outer harness connection points and setting anchors associated therewith to fix the positions of the harness connection points, connecting together vertical edges of the fence cloth of successive modular fence sections together at the locations of said interconnecting grid ropes, and connecting the inner and outer harness ropes of such modular fence sections to the inner and outer harness connection points to assemble the modular fence sections into a fence enclosing the selected surface area.

2. The method of installing a contaminant constraining floating fence structure as defined in claim 1, wherein the lay ing out of the inner grid rope pattern includes laying out a first elongated grid rope extending along a selected center axis of the fence enclosure, laying out transverse grid ropes connected to said longitudinal grid rope at spaced locations and extending along axes transverse to the axis of the longitudinal grid rope and connected at their outer ends to the inner harness connection points, and laying out radial grid ropes from selected points adjacent opposite ends of the longitudinal grid rope to define radial grid ropes terminating outwardly at inner harness connection points to locatecurved end portions of the fence enclosure.

3. A method of installing a contaminant constraining floating fence structure as defined in claim 1, wherein the laying out of said grid rope patterns includes laying out a first longitudinal rope along a selected major axis of the fence enclosure, laying out inner grid ropes in a closed loop connected at a pair of spaced points to said first rope and extending along oppositely curving outwardly convex paths relative to the first grid rope to connect in series the inner harness connection points, and laying out outer grid ropes in a closed loop connected at spaced points alined with the axis of the first grid rope and extending along oppositely curving outwardly convex paths lying outwardly of the paths of the inner grid ropes to connect in series the outer connection points.

4. A method of installing a contaminant constraining fence structure as defined in claim 2, wherein the fence is laid out in substantially elliptical configuration in plan having the major axis of the ellipse generally paralleling the predominant water current direction, the first grid rope forming the center line of the ellipse paralleling said major axis, and the steps including laying out outer grid ropes forming a closed loop connecting in series the outer harness connection points, and connecting grid rope sections between respective associated pairs of inner and outer harness connection points, the fence cloth of successive fence sections being connected together at said grid rope sections.

5. A method of installing a contaminant constraining fence structure as defined in claim 3, wherein the fence is laid out in a substantially elliptical configuration in plan having the major axis of the ellipse generally paralleling the predominant water current direction, the first grid rope forming the center line of the ellipse paralleling said major axis, and the steps including connecting grid rope sections between respective associated pairs of inner and outer harness connection points, the fence cloth of successive fence sections being connected together at said grid rope sections.

6. A contaminant constraining floating fence structure comprising a plurality of modular fence sections to be assembled together to encloseat least in part a selected water surface area, each fence section comprising a plurality of vertically elongated strut members to be arranged in vertical planes having horizontal top and bottom elongated connecting stringers respectively interconnecting the tops and bottoms of the strut members, each strut member including buoyant means to support the same in the water with a selected portion of the strut above the water surface, vertically spaced sets of harness ropes extending from the tops and bottoms of the strut members along vertically converging paths to harness couplings, means connected to the harness couplings to maintain the same at selected levels relative to the water surface, and a cloth web forming the fence portion of each modular fence section spanning the horizontal length of each respective modular section and having a vertical width greater than the height of the strut members, the cloth web being connected at its upper and lower margins to said stringers along the major length thereof and being capable of bowing away from the strut members at the midregions thereof responsive to forces of relative water movement.

7. A contaminant constraining floating fence structure as defined in claim 6, wherein said strut members each comprise first and second vertical bowed substantially rigid tubes interconnected together by horizontal bracing similar tube sections, the first tube being bowed about an are having a longer radius of curvature thanthe second tube and being nearer to the cloth web, and a strut float secured to the second tube member to sustain the strut member with a selected portion thereof projecting above the water surface.

8. A contaminant constraining floating fence structure as defined in claim 6, wherein a plurality of said modular fence sections are connected together in a substantially semicircular pattern in plan to define a concave sweeping fence facing forwardly in a selected direction of travel, the structure including radial ropes extending from selected hub points to said harness couplings of the fence sections, towing ropes extending generally forwardly from the endmost fence sections and from said hub points for towing the fence, and purse string ropes extending transversely between the forwardmost end portions of the fence and forwardly therefrom for opening and closing the forward portion of the fence.

9. A contaminant constraining floating fence structure comprising a plurality of modular fence sections to be assembled together in a substantially elliptical configuration in plan having a major axis generally paralleling the predominant direction of relative water currents to enclose a selected water surface area, each fence section comprising a plurality of vertically elongated strut members to be arranged in vertical planes having horizontal top and bottom elongated connecting stringers respectively interconnecting the tops and bottoms of the strut members, each strut member including buoyant strut float means to support the same in the water with a selected portion of the strut above the water surface, inner and outer vertically spaced sets of harness ropes extending inwardly and outwardly, respectively, from the tops and bottoms of the strut members along paths lying in vertically converging planes to inner and outer harness couplings, float members connected to each of the inner and outer harness couplings to maintain the same at selected levels relative to the water surface, and a cloth web forming the fence portion of each modular fence section uninterruptedly spanning the horizontal length of each respective modular section and having a vertical width greater than the height of the strut members, the cloth web being connected at its upper and lower margins to said stringers along the major length thereof and being capable of bowing away from the strut members at the midregions thereof responsive to forces of relative water movement, and means at the adjacent vertical edges of the cloth webs. of adjacent fence sections for releasably connecting them together along the whole height thereof.

10. A contaminant constraining floating fence structure as defined in claim 9, wherein said strut members each comprise first and second vertical bowed substantially rigid tubes interconnected together by horizontal bracing similar tube sections, the first tube being bowed about an are having a longer radius of curvature than the second tube and being nearer to the cloth web, and said strut float means being secured to the second tube member.

1111. A contaminant constraining floating fence structure as defined in claim 9, including a longitudinal grid rope extending between first and second ends along said major axis, radial grid ropes extending from said ends to inner connection points for the inner harness coupling for fence sections at opposite end portions of the fence, transverse grid ropes connected to said longitudinal grid rope at spaced locations having first sections extending to inner connection points for inner harness couplings for other fence sections and having second sections extending outwardly therefrom to outer connection points for the outer harness couplings, and outer grid ropes connecting in series the outer connection points for the outer harness couplings for all of the fence sections.

12. A contaminant constraining floating fence structure as defined in claim 9 including a longitudinal grid rope extending between first and second ends along said major axis, inner grid ropes connected in series at the inner connection points for the inner harness couplings and defining an inner closed loop having a pair of oppositely curving outwardly convex segments joined to the ends of the longitudinal grid rope, outer grid ropes connected in series at the outer connection points for the outer harness couplings defining an outer closed loop spaced outwardly from .and generally corresponding to the configuration of the inner closed loop, and grid rope members interconnecting respective pairs of inner and outer connection points.

13. A contaminant constraining floating fence structure as defined in claim 12, including a shackle at each of said connection points interconnecting adjacent pairs of the grid ropes defining the inner and outer closed loops and having a plurality of snap hooks fastened by links to each shackle for connection to one of the grid rope members and to a harness couplings of each of a pair of adjacent fence sections.

14. A contaminant constraining fence structure as defined in claim 9 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of the fence path in regions where the fence crosses said major axis.

Ms. A contaminant constraining fence structure as defined in claim 10 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of 

1. A method of installing in position in the water a contaminant constraining floating fence structure made up of plural, releasably connectable, modular fence sections to be assembled together to enclose a selected water surface area, the modular floating fence sections being of the type having plural vertically arranged struts to be sustained at a selected level in the water with top and bottom stringers therebetween and a fence cloth spanning the horizontal length of the section and supported along its upper and lower edges by the stringers, and sets of inner and outer harness ropes extending from the tops and bottoms of the struts; the method comprising the steps of laying out inner and outer grid rope patterns defining inner and outer harness connection points and interconnecting grid ropes for locating the modular fence sections in proper relationship to surround the surface area to be enclosed, connecting buoy floats to the inner and outer harness connection points to sustain the connection points at identifiable locations near the water surface, laying out anchor lines connected to the outer harness connection points and setting anchors associated therewith to fix the positions of the harness connection points, connecting together vertical edges of the fence cloth of successive modular fence sections together at the locations of said interconnecting grid ropes, and connecting the inner and outer harness ropes of such modular fence sections to the inner and outer harness connection points to assemble the modular fence sections into a fence enclosing the selected surface area.
 2. The method of installing a contaminant constraining floating fence structure as defined in claim 1, wherein the laying out of the inner grid rope pattern includes laying out a first elongated grid rope extending along a selected center axis of the fence enclosure, laying out transverse grid ropes connected to said longitudinal grid rope at spaced locations and extending along axes transverse to the axis of the longitudinal grid rope and connected at their outer ends to the inner harness connection points, and laying out radial grid ropes from selected points adjacent opposite ends of the longitudinal grid rope to define radial grid ropes terminating outwardly at inner harness connectIon points to locate curved end portions of the fence enclosure.
 3. A method of installing a contaminant constraining floating fence structure as defined in claim 1, wherein the laying out of said grid rope patterns includes laying out a first longitudinal rope along a selected major axis of the fence enclosure, laying out inner grid ropes in a closed loop connected at a pair of spaced points to said first rope and extending along oppositely curving outwardly convex paths relative to the first grid rope to connect in series the inner harness connection points, and laying out outer grid ropes in a closed loop connected at spaced points alined with the axis of the first grid rope and extending along oppositely curving outwardly convex paths lying outwardly of the paths of the inner grid ropes to connect in series the outer connection points.
 4. A method of installing a contaminant constraining fence structure as defined in claim 2, wherein the fence is laid out in substantially elliptical configuration in plan having the major axis of the ellipse generally paralleling the predominant water current direction, the first grid rope forming the center line of the ellipse paralleling said major axis, and the steps including laying out outer grid ropes forming a closed loop connecting in series the outer harness connection points, and connecting grid rope sections between respective associated pairs of inner and outer harness connection points, the fence cloth of successive fence sections being connected together at said grid rope sections.
 5. A method of installing a contaminant constraining fence structure as defined in claim 3, wherein the fence is laid out in a substantially elliptical configuration in plan having the major axis of the ellipse generally paralleling the predominant water current direction, the first grid rope forming the center line of the ellipse paralleling said major axis, and the steps including connecting grid rope sections between respective associated pairs of inner and outer harness connection points, the fence cloth of successive fence sections being connected together at said grid rope sections.
 6. A contaminant constraining floating fence structure comprising a plurality of modular fence sections to be assembled together to enclose at least in part a selected water surface area, each fence section comprising a plurality of vertically elongated strut members to be arranged in vertical planes having horizontal top and bottom elongated connecting stringers respectively interconnecting the tops and bottoms of the strut members, each strut member including buoyant means to support the same in the water with a selected portion of the strut above the water surface, vertically spaced sets of harness ropes extending from the tops and bottoms of the strut members along vertically converging paths to harness couplings, means connected to the harness couplings to maintain the same at selected levels relative to the water surface, and a cloth web forming the fence portion of each modular fence section spanning the horizontal length of each respective modular section and having a vertical width greater than the height of the strut members, the cloth web being connected at its upper and lower margins to said stringers along the major length thereof and being capable of bowing away from the strut members at the midregions thereof responsive to forces of relative water movement.
 7. A contaminant constraining floating fence structure as defined in claim 6, wherein said strut members each comprise first and second vertical bowed substantially rigid tubes interconnected together by horizontal bracing similar tube sections, the first tube being bowed about an arc having a longer radius of curvature than the second tube and being nearer to the cloth web, and a strut float secured to the second tube member to sustain the strut member with a selected portion thereof projecting above the water surface.
 8. A contaminant constraining floating fence structure as Defined in claim 6, wherein a plurality of said modular fence sections are connected together in a substantially semicircular pattern in plan to define a concave sweeping fence facing forwardly in a selected direction of travel, the structure including radial ropes extending from selected hub points to said harness couplings of the fence sections, towing ropes extending generally forwardly from the endmost fence sections and from said hub points for towing the fence, and purse string ropes extending transversely between the forwardmost end portions of the fence and forwardly therefrom for opening and closing the forward portion of the fence.
 9. A contaminant constraining floating fence structure comprising a plurality of modular fence sections to be assembled together in a substantially elliptical configuration in plan having a major axis generally paralleling the predominant direction of relative water currents to enclose a selected water surface area, each fence section comprising a plurality of vertically elongated strut members to be arranged in vertical planes having horizontal top and bottom elongated connecting stringers respectively interconnecting the tops and bottoms of the strut members, each strut member including buoyant strut float means to support the same in the water with a selected portion of the strut above the water surface, inner and outer vertically spaced sets of harness ropes extending inwardly and outwardly, respectively, from the tops and bottoms of the strut members along paths lying in vertically converging planes to inner and outer harness couplings, float members connected to each of the inner and outer harness couplings to maintain the same at selected levels relative to the water surface, and a cloth web forming the fence portion of each modular fence section uninterruptedly spanning the horizontal length of each respective modular section and having a vertical width greater than the height of the strut members, the cloth web being connected at its upper and lower margins to said stringers along the major length thereof and being capable of bowing away from the strut members at the midregions thereof responsive to forces of relative water movement, and means at the adjacent vertical edges of the cloth webs of adjacent fence sections for releasably connecting them together along the whole height thereof.
 10. A contaminant constraining floating fence structure as defined in claim 9, wherein said strut members each comprise first and second vertical bowed substantially rigid tubes interconnected together by horizontal bracing similar tube sections, the first tube being bowed about an arc having a longer radius of curvature than the second tube and being nearer to the cloth web, and said strut float means being secured to the second tube member.
 11. A contaminant constraining floating fence structure as defined in claim 9, including a longitudinal grid rope extending between first and second ends along said major axis, radial grid ropes extending from said ends to inner connection points for the inner harness coupling for fence sections at opposite end portions of the fence, transverse grid ropes connected to said longitudinal grid rope at spaced locations having first sections extending to inner connection points for inner harness couplings for other fence sections and having second sections extending outwardly therefrom to outer connection points for the outer harness couplings, and outer grid ropes connecting in series the outer connection points for the outer harness couplings for all of the fence sections.
 12. A contaminant constraining floating fence structure as defined in claim 9 including a longitudinal grid rope extending between first and second ends along said major axis, inner grid ropes connected in series at the inner connection points for the inner harness couplings and defining an inner closed loop having a pair of oppositely curving outwardly convex segments joined to the ends of the longitudinal grid rope, outer grid ropes connected in series at the outer connection points for the outer harness couplings defining an outer closed loop spaced outwardly from and generally corresponding to the configuration of the inner closed loop, and grid rope members interconnecting respective pairs of inner and outer connection points.
 13. A contaminant constraining floating fence structure as defined in claim 12, including a shackle at each of said connection points interconnecting adjacent pairs of the grid ropes defining the inner and outer closed loops and having a plurality of snap hooks fastened by links to each shackle for connection to one of the grid rope members and to a harness couplings of each of a pair of adjacent fence sections.
 14. A contaminant constraining fence structure as defined in claim 9 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of the fence path in regions where the fence crosses said major axis.
 15. A contaminant constraining fence structure as defined in claim 10 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of the fence path in regions where the fence crosses said major axis.
 16. A contaminant constraining fence structure as defined in claim 11 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of the fence path in regions where the fence crosses said major axis.
 17. A contaminant constraining fence structure as defined in claim 12 including a plurality of anchors having anchor lines extending therefrom, means for coupling at least one anchor line to each of said outer harness couplings, and means for coupling plural anchor lines to outer harness couplings of selected ones of the fence sections defining curved sections of the fence path in regions where the fence crosses said major axis.
 18. A contaminant constraining fence structure as defined in claim 6, including a settling tank vessel coupled to a portion of the fence structure to receive floating contaminant from the constrained water surface area, the fence cloth web having an opening therein located immediately below the water level and extending above the level of the floating contaminant, the settling tank vessel including a receptacle portion and an inlet through portion extending forwardly therefrom secured to the cloth web along edges thereof bounding said opening for passage of contaminant and some water through the opening and trough portion into the receptacle portion, and tank buoyant means for sustaining the settling tank vessel in floating condition adjacent the water level.
 19. A contaminant constraining fence structure as defined in claim 9, including a settling tank vessel coupled to a portion of the fence structure to receive floating contaminant from the constrained water surface area, the fence cloth web having an opening therein located immediately below the water level and extending above the level of the floating contaminant, the settling tank vessel including a receptacle portion and an inlet trough portion extending forwardly therefrom secured to the cloth web along edges thereof bounding said opening for passage of contaminant and some water through the opening and trough portion into the receptacle portion, and tank buoyant means for sustaining the settling tank vessel in floating condition adjacent the water level.
 20. A contaminant constraininG fence structure as defined in claim 18, wherein said settling tank vessel includes a plurality of closed tube members to be selectively filled with air or water and forming a cagelike supporting framework for the settling tank vessel and a cloth skin secured to said framework and forming the vessel walls enclosing the receptacle portion thereof.
 21. A contaminant constraining fence structure as defined in claim 19, wherein said settling tank vessel includes a plurality of closed tube members to be selectively filled with air or water and forming a cagelike supporting framework for the settling tank vessel and a cloth skin secured to said framework and forming the vessel walls enclosing the receptacle portion thereof.
 22. A contaminant constraining fence structure as defined in claim 18, including means providing a normally closed water outlet in a lowermost region of the receptacle portion of the settling tank vessel which can be selectively opened for passage of water out of the lower regions of said receptacle portion as contaminant accumulates therein.
 23. A contaminant constraining fence structure as defined in claim 19, including means providing a normally closed water outlet in a lowermost region of the receptacle portion of the settling tank vessel which can be selectively opened for passage of water out of the lower regions of said receptacle portion as contaminant accumulates therein. 